Making long chains generate coupling and ripple effect.
Any chain change breaks the code.

TL;DR: Just sent messages to your acquaintances.

Problems

• Coupling

• Break encapsulation

Solutions

• Create intermediate methods.
• Think about Law of Demeter.
• Create higher level messages.

Sample Code

Wrong

class Dog {
   constructor(feet) {
     this.feet = feet;    
  }
  getFeet() {    
    return this.feet;
  }  
}

class Foot {
  move(){    
    //..
  }
}

feet = [new Foot(), new Foot(), new Foot(), new Foot()];
dog = new Dog(feet);

for (var foot of dog.getFeet()) {
  foot.move(); 
}

Right

class Dog {
   constructor(feet) {
     this.feet = feet;    
  }
  walk(){
    for (var foot of this.feet) {
      foot.move(); 
    }
  }
}

class Foot {
  move(){    
    //..
  }
}

feet = [new Foot(), new Foot(), new Foot(), new Foot()];
dog = new Dog(feet);
dog.walk();

Detection

Automatic detection is possible using parsing trees.

Also Known as

• Message Chains

• Law of Demeter

Relations

Code Smell 67 - Middle Man

Maxi Contieri ・ Apr 12 '21

#webdev #codenewbie #tutorial #oop

More Info

• Refactoring Guru

Tags

• Declarative

• Encapsulation

Conclusion

Avoid successive message calls. Try to hide the intermediate collaborations and create new protocols.

Credits

Photo by Chewy on Unsplash

This article is part of the CodeSmell Series.

How to Find the Stinky parts of your Code

Maxi Contieri ・ May 21 '21

#codenewbie #tutorial #codequality #beginners

Last update: 2021/06/10